1. Field of the Invention
The present invention relates to a zoom lens system suitable for a single-lens reflex camera, a digital camera, and the like.
2. Related Background Art
In a fast wide-angle zoom lens system suitable for a single-lens reflex camera, a digital camera, and the like, there are disclosed a four-lens-group zoom lens system and a five-lens-group zoom lens system each having a leading lens group with negative refractive power in Japanese Patent Application Laid-Open Nos. 2001-174704 and 2001-318314.
However, in a four-lens-group zoom lens system having negative-positive-negative-positive power distribution, although an angle of view of 80 degrees or more is accomplished in a wide-angle end state, it has been extremely difficult to correct astigmatism and distortion excellently.
In an example disclosed in Japanese Patent Application Laid-Open No. 2001-174704, although a five-lens-group zoom lens system having a leading lens group with negative refractive power has a fast aperture ratio of about 2.8, the maximum angle of view is merely about 75 degrees.
In an example disclosed in Japanese Patent Application Laid-Open No. 2001-318314, although a five-lens-group zoom lens system having a leading lens group with negative refractive power has the maximum angle of view of 100 degrees or more, the zoom ratio is small about 2.7 and an f-number is merely about 4.